Network systems that provide reliable delivery of information typically use some form of acknowledgments (ACKs) or negative acknowledgments (NAKs) to notify a sender that data transmitted from a source is properly received at a target device. For instance, the TCP/IP (Transfer Control Protocol/Internet Protocol) supports bi-directional data message traffic where feedback messages in a reverse direction of a data block transmission indicate whether or not the block of data is properly received at a target device.
Most packet-switched systems in which digital information is transmitted over a wireless, bidirectional link attempt to improve efficiency and maximize capacity by allocating bandwidth on an as-needed basis. That is, a reverse direction traffic channel for carrying acknowledgment messages as previously discussed is allocated for use only when such messages become available for transmission to a source in response to the reception of data at a target device. In these systems, bandwidth must be allocated and deallocated dynamically so that wireless resources for transmitting ACK messages are not dedicated when no ACK messages are being transmitted. This process of allocating and de-allocating traffic channels for the transmission of these sporadically generated ACK messages is cumbersome because there is substantial overhead processing required to allocate and deallocate channels to multiple subscriber units competing for their use. In this instance, wireless resources are wasted to the extent that channels cannot be utilized in a reverse link until a confirmation is received from a subscriber unit that a channel is properly assigned. Thus, there can be a substantial delay between the time a subscriber wishes to transmit and the time it is able to do so.
Rather than assigning channels on an as-needed basis, a wholly dedicated wireless channel in a reverse direction can be allocated for use by a particular subscriber unit to support the transmission of sporadically generated messages. However, the continuous allocation of an entire channel for such messages is often a waste of resources, especially when multiple users are competing for their use and the channel is capable of carrying much more traffic than merely occasional messages.